Doctors aren’t sure what causes stomach cancer. There is a strong correlation between a diet high in smoked and salted foods and stomach cancer. As the use of refrigeration for preserving foods has increased around the world, the rates of stomach cancer have declined.
In general, cancer begins when an error (mutation) occurs in a cell’s DNA. The mutation causes the cell to grow and divide at a rapid rate and to continue living when a normal cell would die. The accumulating cancerous cells form a tumor that can invade nearby structures. And cancer cells can break off from the tumor to spread throughout the body.
The cells that form the tumor determine the type of stomach cancer. The type of cells in your stomach cancer helps determine your treatment options. Types of stomach cancer include:
- Cancer that begins in the glandular cells (adenocarcinoma): The glandular cells that line the inside of the stomach secrete a protective layer of mucus to shield the lining of the stomach from the acidic digestive juices. Adenocarcinoma accounts for the great majority of all stomach cancers.
- Cancer that begins in immune system cells (lymphoma): The walls of the stomach contain a small number of immune system cells that can develop cancer. Lymphoma in the stomach is rare.
- Cancer that begins in hormone-producing cells (carcinoid cancer): Hormone-producing cells can develop carcinoid cancer. Carcinoid cancer in the stomach is rare.
- Cancer that begins in nervous system tissues: A gastrointestinal stromal tumor (GIST) begins in specific nervous system cells found in your stomach. GIST is a rare form of stomach cancer.
Because the other types of stomach cancer are rare, when people use the term “stomach cancer” they generally are referring to adenocarcinoma.